In the field of construction and maintenance of structures, scaffolding is typically required in order to place workers and materials at elevated work areas. The scaffolding is vertically erected alongside the building and may include several levels, as dictated by the heights which must be reached, with each level serving as a platform for support of workers and materials. When work is completed, the scaffolding is removed or disassembled as it is no longer needed.
Scaffolding is by definition a temporary structure, and many forms of prefabricated scaffolding are available to provide a reusable scaffolding system for scaffolding users. A type of prefabricated scaffolding commonly used in construction of buildings, for example, includes end frames having two support columns with a horizontal cross-bar connecting the two scaffolding columns at the upper ends of the columns. Walk boards, typically in the form of wooden planks, are simply laid across the horizontal cross-bars of adjacent end frames so that one end of a plank rests upon the cross-bar of one end frame with the other end of the plank resting on the cross-bar of an adjacent end frame. Successive ones of the end frames are connected to one another by cross-bracing each support column of each end frame to corresponding support columns of adjacent end frames. Planks are typically longer than the distance from end frame to end frame so the plank overlaps the end frame to some degree.
Several undesirable consequences result from this approach. For example, a scaffolding structure as described above exhibits limited utility since the cross-braces on the working side of the scaffolding (i.e., the side which faces the building under construction) represent an obstacle which inhibits access to the building by workers. To avoid the cross-braces, workers often remove them and thereby compromise the structural integrity of the scaffolding in order to improve access to the building. The necessary placement of workers and materials at the same level of the scaffolding structure further restricts the worker's ability to move freely about, creating an additional hazardous condition for the worker and others.
Scaffolding of the type described above is also structurally unstable when workers and materials are placed at higher levels of the scaffolding structure. Forces exerted at upper levels of the structure, such as the effect of wind, movement of workers and materials, and the like, can easily exceed the scaffolding's limits, causing it to topple. To prevent such an occurrence, it is common practice to secure the scaffolding by chain or rope to the building itself whenever possible.
Another difficulty with the use of conventional scaffolding structures is that they are difficult and hazardous to ascend and descend. Truss members used for adding structural strength between the columns and cross-bar are often used by workers for climbing the scaffolding. However, these truss members are load-bearing members of the scaffolding end frame and are not designed to meet applicable industry standards (including OSHA standards) for climbing apparatus. Overlapped planks are also a safety hazard since workers can trip over the ends of the planks or upend a plank by stepping on the overhang.
Still another problem arising from the use of conventional scaffolding is most prevalent in higher scaffolding where electrical tools are required. In such instances, electrical lines are extended from the ground to the level at which electrical power is required. However, dangling electrical lines tend to be pulled downward by the effects of gravity and other forces, resulting in an inconvenience to the worker and a hazard to equipment and other workers at lower levels.
The following list of U.S. Patents represent scaffolding types which are typical of the art.
U.S. Pat. No. Inventor(s) Issue Date 2,305,563 R. A. Uecker, et al. Dec. 15, 1942 2,449,069 H. A. Harrison Sep. 14, 1948 2,555,782 R. G. Brownstein Jun 5, 1951 3,726,362 J. D. Puckett Apr 10, 1973 4,391,348 R. L. Rieland Jul 5, 1983 4,430,839 G. Buffers Feb 14, 1984 4,891,926 D. Alenbaugh Jan 9, 1990 5,388,661 R. Hood, Jr. Feb 14, 1995 5,400,870 S. Inoue Mar 28, 1995 5,412,913 H. F. Daniels, et al. May 9, 1995
None of these scaffold structures solve the problems discussed above.
What is needed, therefore, is an easily assembled scaffolding structure which enhances the placement, access, movement, and safety of workers and materials at elevated work areas.